body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #333;
    font-family: Arial, sans-serif;
}

.game-container {
    width: 450px;
    margin: auto;
    text-align: center;
}

.chessboard {
    display: grid;
    grid-template-columns: repeat(15, 30px);
    grid-template-rows: repeat(15, 30px);
    background-color: #fff;
    border: 3px solid #333;
    margin: 20px auto;
}

.cell {
    width: 30px;
    height: 30px;
    background-color: #f3f3f3;
    border: 1px solid #ccc;
    position: relative;
}

.chessman {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    position: absolute;
    top: 1px;
    left: 1px;
    cursor: pointer;
}

.black {
    background-color: #000;
}

.white {
    background-color: #c0c0c0;
}

/* 禁用已下棋的单元格 */
.disabled {
    pointer-events: none;
}

.cool-button {
    padding: 10px 20px;
    font-size: 16px;
    color: #fff;
    background-color: #3498db;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    outline: none;
    position: relative;
    overflow: hidden;
    z-index: 1;
    transition: transform 0.2s;
}

.cool-button::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle, transparent 0, transparent 50%, #3498db 50%, #3498db 100%);
    z-index: -1;
    transform: scale(2);
    transition: transform 0.5s ease-out;
}

.cool-button:hover::before {
    transform: scale(2);
}

.cool-button::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, #fff 0, #fff 50%, transparent 50%, transparent 100%);
    border-radius: 50%;
    transform: translate(-50%, -50%) scale(0);
    transition: transform 0.3s cubic-bezier(0.55, 0.05, 0.675, 0.19);
    z-index: 0;
}

.cool-button:active::after {
    transform: translate(-50%, -50%) scale(2);
}